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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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    <style>
        div {
            border: 1px solid;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="row">
            <div class="col-1">1</div>
            <div class="col-1">2</div>
            <div class="col-1">3</div>
            <div class="col-1">4</div>
            <div class="col-1">5</div>
            <div class="col-1">6</div>
            <div class="col-1">7</div>
            <div class="col-1">8</div>
            <div class="col-1">9</div>
            <div class="col-1">10</div>
            <div class="col-1">11</div>
            <div class="col-1">12</div>
        </div>
    </div>

    <div class="container">
        <div class="row">
            <div class="col-sm-6">6</div>
            <div class="col-sm-4">4</div>
            <div class="col-sm-2">2</div>
        </div>
    </div>

    <!-- 
        根据不同屏幕的大小来适配不同的宽度，最终显示不同的样式
    -->
    <div class="container">
        <div class="row">
            <!-- 
                屏幕大时按照md分为9 3 
                屏幕小时按照sm分为1 11
            -->
            <div class="col-sm-1 col-md-9">1</div>
            <div class="col-sm-11 col-md-3">11</div>
        </div>
    </div>
</body>

</html>